Sgt. Darwin Cornejo listens to a student while teaching Never Leave a Marine Behind aboard Marine Corps Base Camp Lejeune Aug. 2. Cornejo thought several classes to junior Marines and noncommissioned officers from Headquarters and Support Battalion. - Sgt. Darwin Cornejo listens to a student while teaching Never Leave a Marine Behind aboard Marine Corps Base Camp Lejeune Aug. 2. Cornejo thought several classes to junior Marines and noncommissioned officers from Headquarters and Support Battalion.